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Abstract:

A method of manufacturing a hydrophobic coating material, including: (a)
mixing a siloxane precursor, water, and a catalyst to proceed with a
sol-gel reaction to form a solution having particles therein, wherein the
sol-gel reaction is performed without using any organic solvent; (b)
chemically modifying the particles with a hydrophobic agent to form
surface-modified particles; and (c) adding a surfactant to the solution
containing the surface-modified particles to form a hydrophobic coating
material. A hydrophobic coating material and a hydrophobic coating formed
by the hydrophobic coating material are also provided. The hydrophobic
coating material may preferably have a low VOC (Volatile organic
compound) value, and may disperse in a water phase solution.

Claims:

1. A method of manufacturing a hydrophobic coating material, comprising
(a) mixing a siloxane precursor, water, and a catalyst to proceed with a
sol-gel reaction to form a solution having particles therein, wherein the
sol-gel reaction is performed without using any organic solvent; (b)
chemically modifying the particles with a hydrophobic agent to form
surface-modified particles; and (c) adding a surfactant to the solution
containing the surface-modified particles to form a hydrophobic coating
material.

2. The method of manufacturing a hydrophobic coating material as claimed
in claim 1, wherein steps (a), (b), and (c) are performed with the
following weight ratios: 0.01-30 parts by weight of the siloxane
precursor; 50-99.9 parts by weight of the water; 0.01-5 parts by weight
of the catalyst; 0.01-30 parts by weight of the hydrophobic agent; and
0.01-5 parts by weight of the surfactant.

3. The method of manufacturing a hydrophobic coating material as claimed
in claim 1, wherein steps (a), (b), and (c) are performed with the
absence of any organic solvent.

4. The method of manufacturing a hydrophobic coating material as claimed
in claim 1, wherein the siloxane precursor has a --SiOR or --SiOH
functional group, wherein R is CnH2n+1, and n is a positive
integer.

6. The method of manufacturing a hydrophobic coating material as claimed
in claim 1, wherein the surfactant comprises an anion surfactant, a
combination of an anion surfactant and a cation surfactant, a combination
of an anion surfactant and a non-ionic surfactant, a combination of anion
surfactant and an amphoteric surfactant, or combinations thereof.

7. The method of manufacturing a hydrophobic coating material as claimed
in claim 1, wherein step (a) is performed at 15.degree. C. to 40.degree.
C. for 1 hr to 3.5 hrs.

8. The method of manufacturing a hydrophobic coating material as claimed
in claim 1, wherein step (c) is performed at 15.degree. C. and 40.degree.
C. for 12 hrs to 24 hrs.

9. A hydrophobic coating material manufactured by the method as claimed
in claim 1.

10. A hydrophobic coating manufacturing method comprising the steps of:
providing a hydrophobic coating material as claimed in claim 9; coating
the hydrophobic coating material onto a substrate; and drying or curing
the hydrophobic coating material to form a hydrophobic coating.

11. The hydrophobic coating as claimed in claim 10, wherein a water
contact angle of the hydrophobic coating is larger than 90.degree..

12. The hydrophobic coating as claimed in claim 10, further comprising,
before coating the hydrophobic coating material onto the substrate,
mixing the hydrophobic coating material with a second coating material to
form a mixed coating material formula, and then coating the mixed coating
material formula onto the substrate.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This Application claims priority of Taiwan Patent Application No.
100136706, filed on Oct. 11, 2011, the entirety of which is incorporated
by reference herein.

BACKGROUND OF THE DISCLOSURE

[0002] 1. Field of the Invention

[0003] The present disclosure relates to a coating material, and in
particular relates to a hydrophobic antifouling coating material and a
method for manufacturing the same.

[0004] 2. Description of the Related Art

[0005] In general, surfaces of all substrates are easily stained after
use, and cleaning of some of them is very difficult or requires using
highly corrosive detergents. Using these detergents might be harmful for
humans and the environment. Therefore, various antifouling or
self-cleaning materials have been developed to maintain cleanliness.

[0006] However, for today's processes for manufacturing antifouling
coating materials, such as in a sol-gel reaction process, great amounts
of organic solvents (such as alcohols, toluene, tetrahydrofuran, and
etc.) are required. Thus, the resulting coating materials contain a high
quantity of organic solvents (for example, over 90 wt%.) These coating
materials have high volatile organic compound (VOC) value, for example,
between 800 g/L and 900 g/L or even higher, therefore resulting in
environmental pollution.

[0007] Conventionally, in a sol-gel reaction for manufacturing a
hydrophobic antifouling coating material, the reaction must be performed
in an organic solvent due to the reactants being unstable in an aqueous
phase solution, or having phase separation or gelation problems. Although
some waterborne resins, such as waterborne polyurethane (waterborne PU),
have been used to perform a sol-gel reaction in an aqueous phase
solution, some organic solvents are still required in the process to
stabilize the reaction. In addition, the resulting coating materials
usually have poor hydrophobicity, and therefore are not appropriate to be
used as good antifouling materials. Furthermore, waterborne polyurethane
has poor weather-resistance and hardness, and is not suitable to be used
outdoors. Moreover, the molecular weight of the waterborne polyurethane
is large and it has poor compatibility in existing systems, such that its
applications are limited.

[0008] Therefore, a novel antifouling coating material with a low VOC
value is now required.

BRIEF SUMMARY OF THE DISCLOSURE

[0009] An embodiment of the disclosure provides a method of manufacturing
a hydrophobic coating material, comprising: (a) mixing a siloxane
precursor, water, and a catalyst to proceed with a sol-gel reaction to
form a solution having particles therein, wherein the sol-gel reaction is
performed without using any organic solvent; (b) chemically modifying the
particles with a hydrophobic agent to form surface-modified particles;
and (c) adding a surfactant to the solution containing the
surface-modified particles to form a hydrophobic coating material.

[0010] Another embodiment of the disclosure provides a hydrophobic coating
material manufactured by the previously described method.

[0011] Another embodiment of the disclosure provides a hydrophobic coating
manufacturing method comprising the steps of: providing the previously
described hydrophobic coating material; coating the hydrophobic coating
material onto a substrate; and drying or curing the hydrophobic coating
material to form a hydrophobic coating.

[0012] A detailed description is given in the following embodiments with
reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention can be more fully understood by reading the
subsequent detailed description and examples with references made to the
accompanying drawings, wherein:

[0014] FIG. 1 illustrates a method for manufacturing a hydrophobic coating
material according to one embodiment of the disclosure.

[0015]FIG. 2 illustrates a formula of step 102 of FIG. 1 according to one
embodiment of the disclosure.

[0016]FIG. 3 illustrates a formula of step 104 of FIG. 1 according to one
embodiment of the disclosure.

[0017]FIG. 4 illustrates a hydrophobic coating according to one
embodiment of the disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0018] The following description is of the best-contemplated mode of
carrying out the invention. This description is made for the purpose of
illustrating the general principles of the invention and should not be
taken in a limiting sense. The scope of the invention is best determined
by reference to the appended claims.

[0019] Moreover, the formation of a first feature over and on a second
feature in the description that follows may include embodiments in which
the first and second features are formed in direct contact, and may also
include embodiments in which additional features may be formed between
the first and second features, such that the first and second features
may not be in direct contact.

[0020] In one embodiment, a hydrophobic coating material which can be
manufactured without using any organic solvents is provided. The coating
material can be dispersed into an aqueous phase solution with a low VOC
value and therefore is an eco-friendly coating material.

[0021] FIG. 1 illustrates a method for manufacturing a hydrophobic coating
material according to one embodiment of the disclosure. Referring to FIG.
1, in step 102, a siloxane precursor, water, and a catalyst are mixed to
proceed with a sol-gel reaction to form a solution having particles
therein.

[0023] In addition, the sol-gel reaction in step 102 may not require any
organic solvent, such that the resulting coating material can have a low
VOC value. By contrast, an organic solvent is generally used in a
conventional sol-gel reaction to stabilize the reactant. Furthermore, the
conventional sol-gel reaction usually requires a long time, for example,
six hours, at room temperature to complete the reaction. However,
inventors of the present application found out that the sol-gel reaction
is preferably reacted for about 1 hr to about 3.5 hrs without using the
organic solvent. It has been confirmed by experiments that, in a sol-gel
reaction process without using any organic solvent, the reactant may be
less stable due to lack of the organic solvent, and when the reaction
time is too long, for example, more than 3.5 hours, the mixed solution
may become gelatinized or precipitated. However, if the reaction time is
not long enough, for example, less than 1 hour, the sol-gel reaction may
be incomplete. The reaction in step 102 may be performed at room
temperature, for example, at 15° C. to 40° C. In one
embodiment, the reaction in step 102 may have a formula as in FIG. 2,
wherein the siloxane precursor is TEOS, for example.

[0024] Referring to FIG. 1, in step 104, a hydrophobic agent is added into
the mixing solution in step 102 to chemically modify the particles in the
solution. The hydrophobic agent may be, for examples, a silicon-based
hydrophobic agent, a fluorine-base hydrophobic agent, a carbohydrate
hydrophobic agent, a hydrocarbon hydrophobic agent, or combinations
thereof. Examples of the silicon-based hydrophobic agent may be siloxane,
silane, silicone, or combinations thereof. Examples of the fluorine-base
hydrophobic agent may be fluorosilane, fluoroalkysilane,
polytetrafluoroethylene (PTFE), polytrifluoroethylene,
polyvinylfluroride, functional fluoroalkyl compound, or combinations
thereof. Examples of the carbohydrate hydrophobic agent or the
hydrocarbon hydrophobic agent may be reactive wax, polyethylene,
polypropylene, or combinations thereof.

[0025] In step 104, since the hydrophobic agent and the solution having
particles therein are separated into two layers (phases) after mixing,
the chemical modifying reaction substantially occurs at the interface
between the solution and the hydrophobic agent. After the reaction
continues for a period of time, for example, after 1 hour to 2 hours, the
hydrophobic agent may be substantially grafted to the particles. The
reaction may be performed at room temperature, for example, at about
15° C. to 40° C. In one embodiment, the reaction in step
104 may be represented by the formula in FIG. 3, wherein the hydrophobic
agent is 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (F-8261, Degussa),
for example.

[0026] Finally, in step 106 of FIG. 1, the surfactant is added into the
solution with modified particles therein to form a hydrophobic coating
material. The surfactant may be, for example, an anion surfactant, a
combination of an anion surfactant and a cation surfactant, a combination
of an anion surfactant and a non-ionic surfactant, a combination of anion
surfactant and an amphoteric surfactant, or combinations thereof.

[0027] In step 106, the remaining hydrophobic agent is brought into the
solution by the surfactant, such that the modification of the particles
is completed. This step usually requires a longer reaction time, such as
between 12 hours and 24 hours. By adding the surfactant, the resulting
hydrophobic coating material (product) can be stable in an aqueous phase
solution, and the product will not be separated into different phases due
to the hydrophobic characteristics even after a period of time. In
addition, the addition of the surfactant should be performed after the
particles in the mixed solution are substantially modified. If the
surfactant and the hydrophobic agent are added into the solution at the
same time, not only will the particles not be modified completely but
phase separation will occur.

[0028] In one embodiment, steps 102, 104, and 106 are performed with the
following weight ratios: 0.01-30 parts by weight of the siloxane
precursor; 50-99.9 parts by weight of the water; 0.01-5 parts by weight
of the catalyst; 0.01-30 parts by weight of the hydrophobic agent; and
0.01-5 parts by weight of the surfactant. In addition, steps 102, 104,
and 106 are performed without using any organic solvent. If there is too
little surfactant, the modification reaction may be incomplete or the
resulting product may not be able to be stable in an aqueous phase
solution. However, if there is too much surfactant, the hydrophobicity of
the resulting coating material may decrease and the cost of the process
may increase.

[0029] A method for manufacturing a coating material in one embodiment
includes steps 102, 104, and 106 in FIG. 1. In one embodiment, step 102
is performed without using any organic solvent. In another embodiment,
steps 102, 104, and 106 are performed without using any organic solvent.
The coating material may have a low VOC value by manufacturing by a
sol-gel reaction without using any organic solvent, and the material can
be used as an eco-friendly coating material.

[0030] Accordingly, by controlling the reaction time, a sol-gel reaction
including mixing a siloxane precursor, water, and a catalyst to form a
solution having particles therein may be performed without using any
organic solvent such that the reactants will not be gelanized. Then, a
hydrophobic agent is added into the mixture to chemically modify the
particles. Since the hydrophobic agent and water is insoluble, the
modification reaction substantially occurs at the interface. After most
of the particles are modified, a surfactant is added into the solution
such that the remaining hydrophobic agent will be brought into the
solution and the modification reaction may be fully completed. In
addition, the surfactant can help the resulting coating material be more
stable in the aqueous phase solution and therefore the retention time of
the coating material can be extended. However, if no surfactant is added
into the solution which has the modified particles therein, the high
hydrophobicity of the modified particles (for example, the particles with
lots of fluorine in their structure) may cause the particles to be
unstable in the aqueous phase solution, and therefore, the mixture may be
separated into two layers after reacting for a certain period time and
applications of the coating material may be limited. On the other hand,
the coating material according to various embodiments of the disclosure
can be stable in an aqueous phase solution due to the surfactant being
added during the manufacturing process. Therefore, the coating material
according to various embodiments of the disclosure can be used in a
broader application. It should be appreciated that a little amount of
organic solvent may also be used during the process when forming a
coating material with low VOC value, and the scope of the disclosure is
not intend to be limiting.

[0031] In addition, according to various embodiments of the disclosure,
hydrophobic modified particles formed by chemical modification are
stabilized in an aqueous phase solution by adding a surfactant.
Therefore, compared to a method in which a hydrophobic material is simply
absorbed on a surface (in other words, a non-chemical modification), the
hydrophobic coating material according to various embodiments of the
disclosure has better weather-resistance since its hydrophobic structures
are chemically bonded onto the particles.

[0032] In one embodiment of the disclosure, a hydrophobic coating material
not only has a much lower VOC value during a sol-gel reaction process,
compatibility of the coating material with materials (such as aqueous
materials, resins, paints, or the like) is also increased. For example,
the hydrophobic coating material may be coated onto a substrate to form a
hydrophobic coating. Advantages of the hydrophobic coating may include,
but are not limit to, a high coating ability, adherence, hydrophobicity,
antifouling, weather-resistance, solvent-resistance, and etc.

[0033] Referring to FIG. 4, the hydrophobic coating material is coated
onto a substrate 200. The hydrophobic coating material is then dried or
cured to form a hydrophobic coating 202. In one embodiment, the
hydrophobic coating 202 is a transparent film with great adherence with
the substrate 200. In addition, a surface of the hydrophobic coating 202
has a good hydrophobicity. For example, a water contact angle of the
hydrophobic coating 202 is larger than 90°, or larger than
100°. Furthermore, the hydrophobic coating material of the
disclosure can be used in various aspects such as being used as an
additive of other coating materials or paints. For example, the
hydrophobic coating material of the disclosure may be mixed with a second
coating material to form a mixed coating material formula. Then, the
mixed coating material formula is coated onto the substrate 200.

EXAMPLES 1-8

Manufacturing Hydrophobic Coating Materials

[0034] 0.8 g of tetraethyl orthosilicate (TEOS), 0.277 g of water, and
0.32 g of HCl (0.1N) were mixed and reacted at room temperature for 3
hours. A solution having particles therein was obtained. Then, 0.8 g of
1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (F-8261, Degussa) was added
into the mixture and reacted at room temperature for 2 hours, such that
the particles were chemically modified. Next, 0.0384 g of sodium dodecyl
sulfate (SDS) was dissolved in 24.94 g of water and added into the
solution having the modified particles as an anion surfactant. The
reaction was performed at room temperature for 12 hours to form a
hydrophobic coating material which was stable in an aqueous solution.
Then, the hydrophobic coating material was coated onto a glass substrate
and baked at 120° C. for 30 minutes. After the coating was cooled
down, the water contact angle of the coating of 116° was measured.

[0035] Table 1 illustrates results of various examples and comparative
examples. The hydrophobic agents F-8261 and 7806 can be represented by
following formula:

##STR00001##

[0036] In addition, surfactant DC 190 refers to a non-ionic surfactant DOW
CORNING® 190 FLUID (bought from DOW CORNING), which includes 40 wt %
to 60 wt % of dimethyl, methyl(propyl(poly(EO)(PO))acetate) siloxane; 30
wt % to 50 wt % of poly(ethylene oxide propylene oxide) monoallyl ether
acetate; and less than 9 wt % of polyelther acetate. CATB refers to cetyl
trimethyl ammonium bromide, which is a cation surfactant. EnviroGem 360
was bought from Air products. AQ55S was bought from Eastman, which is an
anion surfactant. AQ55S had following formula, wherein A is dicarboxylic
acid moiety, G is glycol moiety.

##STR00002##

[0037] SDBS refers to sodium dodecylbenzene sulfate, which is an anion
surfactant. DSS refers to dioctyl sodium sulfosuccinate, which is an
anion surfactant.

[0038] In examples 1 to 8, sol-gel reactions were performed without using
any organic solvent, and an anion surfactant (such as SDS, AQ55S, SDBS,
or DSS) or combinations thereof was added into the reaction, such that
products which were stable in an aqueous phase solution and had great
hydrophobicity (water contact angle>100°) were obtained.

[0039] In comparative example 1, TEOS, water, HCl, and organic solvent
(isopropyl alcohol) were mixed to perform a sol-gel reaction. In
comparative examples 2 to 6, sol-gel reactions were also performed
without using any organic solvent. However, in comparative example 2, no
surfactant was used. In comparative example 3, only a non-ionic
surfactant (AQ55S) was used. In comparative example 4, only a cation
surfactant (DC190) was used. In comparative example 5, only a commercial
surfactant (EnviroGem 360) was used. In comparative example 6, the
commercial coating material EVONIL (Dynasylan® SIVO 112) was used for
comparison with the coating materials of examples 1 to 8.

[0040] Referring to Table 1, according to examples 1 to 8, hydrophobic
coating materials which were stable in an aqueous phase solution and had
great hydrophobicity were manufactured in the sol-gel reactions without
using any organic solvent by adding an appropriate amount of anion
surfactant or combinations thereof during the manufacturing process. On
the contrary, according to comparative example 2, the resulting coating
material which was formed without adding any surfactant during the
process was unstable in an aqueous phase solution, such that the coating
material of comparative example 2 was not able to be coated onto the
glass substrate. Moreover, according to comparative examples 3 to 5,
although the stability can be improved by adding some surfactants,
hydrophobicity of the coating materials of comparative examples 3 to 5
were poor resulting from not using any anion surfactant. In comparative
example 6, a commercial coating material was coated onto a substrate, but
the hydrophobicity of the coating materials of comparative example 6 was
still not as good as the hydrophobicity of the coating materials of
examples 1 to 8.

[0042] Referring to Table 2, the hydrophobic coating of example 1,
compared to the hydrophobic coating of comparative example 1, had a low
VOC value. In the manufacturing process of the hydrophobic coating of the
example 1, no organic solvent was used, and the very low VOC value
resulted from a byproduct (ethanol) of the sol-gel reaction. Therefore,
the eco-friendly hydrophobic coating was formed accordingly.

[0043] While the invention has been described by way of example and in
terms of the preferred embodiments, it is to be understood that the
invention is not limited to the disclosed embodiments. To the contrary,
it is intended to cover various modifications and similar arrangements
(as would be apparent to those skilled in the art). Therefore, the scope
of the appended claims should be accorded the broadest interpretation so
as to encompass all such modifications and similar arrangements.